1. Field of the Invention
The present invention relates to a paper feeding cassette for an image forming apparatus, and more particularly, to a paper feeding cassette removably mounted in an image forming apparatus to contain sheets of paper to be printed therein and supply the sheets to an image forming apparatus body one by one.
2. Description of the Related Art
Referring to FIG. 1, an image forming apparatus, such as a photocopier, a laser printer, a facsimile, and a multi-function device, has a paper feeding cassette 100 in which sheets of paper to be supplied into an image forming apparatus body are stacked. Generally, the paper feeding cassette 100 is removably mounted in the image forming apparatus body. The sheets stacked in the paper feeding cassette 100 are supplied to the image forming apparatus body, one by one, by a pick-up unit.
Referring to FIGS. 2 and 3, the paper feeding cassette 100 includes a cassette body 110, an inclined supporter 130 disposed inside the cassette body 110 at a predetermined slope with respect to an uppermost sheet P, and a separation guide 120 being supported on the inclined supporter 130.
In the above construction, a pickup roller 140 rotates to be in contact with the uppermost sheet P stacked in the paper feeding cassette 100 and pushes up the uppermost sheet P in a direction of “A”. Then, a front end of the sheet P comes into contact with the separation guide 120. At this point, there is a roughness on a surface of the separation guide 120 to which the sheet P contacts. Accordingly, the sheet P is separated one by one due to a friction resistance that is generated when the uppermost sheet P comes into contact with the surface of the separation guide 120, and when the sheet P is slidably picked-up.
Recently, the image forming apparatus has been improved to be capable of performing a printing operation using various types of the sheet P. Accordingly, the paper feeding cassette 100 is available to accommodate the various types of the sheet P.
However, the surface of the separation guide 120 to be in contact with the sheet P is made of a material having a predetermined surface roughness, and the separation guide 120 is fixedly disposed in the cassette body 110. Accordingly, the sheet P is picked-up by the pickup roller 140 with the same friction resistance regardless of the type of the sheet P.
Accordingly, if the separation guide 120 is made of material having a high surface roughness, it is effective in separating a thin sheet P one by one. However, in the same case, the separation guide 120 has a difficulty separating a thick sheet P due to an increased friction resistance, which is attributed to a self-weight of the thick sheet P. Thus, there are problems that the thick sheet P is not picked-up and is jammed in the cassette body 110.
On the other hand, if the separation guide 120 is made of another material having a low surface roughness, it has the effectiveness in separating and picking up the thick sheet P one by one owing to the decreased friction resistance. However, in the same case, since the friction resistance is not generated sufficiently for the separation guide 120 to separate the thin sheet P one by one, there is a problem that the thin sheet P is fed out in an overlapping relationship with other sheets P.